This is an application for a second competing-renewal grant to extend a line of health-services research aimed at adapting services in drug courts to the needs of drug-abusing offenders. Our previous studies demonstrated a reliable and robust matching effect in drug courts, in which certain high-risk participants had significantly better counseling attendance, longer durations of drug abstinence and higher graduation rates when required to attend frequent, bi-weekly judicial status hearings in court. In contrast, low-risk participants performed equivalently regardless of the schedule of court hearings. We replicated this matching effect in two additional jurisdictions and then confirmed it using a prospective matching design, in which outcomes from the matching procedure were shown to be superior to those achieved by drug court as-usual. The current application will examine the incremental utility gained by re-adjusting the dosage of both court hearings and clinical case-management sessions in response to participants'on-going performance in the program. We crafted an adaptive algorithm that distinguishes between non-compliance with supervisory conditions of the drug court (e.g., failing to show for counseling) and non-responsiveness to the interventions (e.g., providing drug-positive urines). We specified increased judicial supervision as the consequence for non- compliance and enhanced clinical case-management services as the consequence for non-responsiveness. We piloted the adaptive algorithm in a small preliminary study (N = 30) to confirm that it is acceptable to both clients and staff, feasible to implement with greater than 85% experimental integrity, and shows substantial promise for eliciting clinically meaningful improvements in both drug abstinence and graduation rates. The estimated effect sizes from the adaptive algorithm ranged from 0.40 to 0.60 across dependent measures, representing a significant increase in effects beyond what was obtained from our baseline-matching procedure alone. Much of the incremental improvement was derived for low-risk participants who had shown minimal effects from the prior matching procedure. We now propose to test the incremental utility of this adaptive algorithm in a fully powered experimental trial. Consenting misdemeanor drug court participants will be randomly assigned at entry to the full adaptive intervention or to baseline-matching only (n = 75 per cell). Primary outcomes will be graduation rates, urine drug-screen results during enrollment in drug court and at 6 and 12 months post-entry, and re-arrest rates at 24 months post-entry. Secondary outcomes will include self-report measures of HIV-risk behaviors, medical health, psychiatric health, family/social relationships and employment. Finally, we will conduct exploratory analyses to identify potential mediating variables that may help explain the process by which the adaptive algorithm improves outcomes. Potential mediators to be examined are (1) the fidelity and timing of adaptive responses, (2) participants'perceptions of procedural justice in the program, (3) participants'perceptions of perceived deterrence and (4) participants'satisfaction with the drug court program. Public Health Relevance: This competing-renewal grant will extend a program of health-services research aimed at adapting services in drug courts to the needs of drug-abusing offenders. Our prior studies demonstrated a reliable and robust baseline-matching effect in drug courts, in which high-risk offenders performed significantly better with intensive supervision from a judge. The current project will examine the incremental utility gained by continuously re-adjusting the intensity of both judicial supervision and clinical case-management services in response to clients'on-going performance in the program.